High frequency oscillatory circuit for therapeutic purposes



HIGH FREQUENCY OSCILLATOHY CIRCUIT FOR THERAPEUTIG PURPOSES Filed NOV, 5, 1950 Patented Nov. 22, 1932 UNITED STATES PATENT OFFICE PAUL C. RAWLS, OF DESI MOINES, IOWA, ASSIGNOB TO TECHNICAL EQUIPMENT COMPANY, OF DES MOINES, IOWA, A CORPORATION OF IOWA man FREQUENCY oscmmronr cmcur'r ron U'rrc ruarosm Application Bled November 3, 1930. Serial Ro. 493,024.

The objectof my invention is to provide an improved high frequency oscillatory circuit particularly adapted to produce extremely high frequency oscillating current for therapeutic purposes, and in which is employed the ordinary'two electrode vacuum tube for producing the necessary high frequency oscillating current, and voltage variations.

Heretofore a considerable diiliculty has been experienced in the application of therapeutics employing high frequency oscillating currents of appreciable amount, due to the fact that it has been impossible to maintain a constant predetermined frequency of oscillation during the' entire time of a single application or` operation, and at the same time be able to vary the amount of current as applied to the treatment through a comparatively large range of time to meet the requirements of the treatment being given. Therefore, the art of therapeutics has not advanced as might be expected, as the success of the method of treatment depends largely on being able to easily and positively control the amount of current and the frequency of its oscillation. l

Especially in view of the limitations of the existing oscillators employing a spark gap, which apparatus is very unreliable in its op eration, it is almost impossible to maintain a constant frequency during the time of a treatment and at the same time vary the amount of current, as any variation of the amount of current results in variation of the frequency of this type of oscillator.

It is, therefore, the object of my invention to provide an improved high frequency oscil lating circuit for therapeutic purposes in which a predetermined frequency of the current oscillation may be positively and easily maintained, for any desired time, and at the same time permitting a comparatively large amount of current variation as applied to the point of application.

A further object is to provide in an oscillatory circuit for therapeutic purposes, and in which is included an electrically operatmg knife, improved means in connection with the kmfe whereby the amount of current may be controlled by the operators thumb,

so that the operator may always have at his command any desired amount of current.'

My invention consists in the construction,

arrangement and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawing, in which:

- Figure 1 is a diagram of my improved os- 0 cillatory circuit.

Figure 2 is a detail sectional view of one form of knife used in connection therewith. My improved oscillatory circuit comprises a pair of vacuum tubes 10 of the type em- 65 ploying a heating filament, a plate and a grid. The laments 11 of the tubes are mounted in parallel relation. The negative ends of the filaments are connected by a conductor 12 and the positive ends of the filament 70 are connected by a conductor 13.` A battery 14 or other suitable current sup ly is provided for heating the filaments. ne side of the battery is connected to the conductor 13 by a conductor 15, and the opposite side of the conductor 12 by a conductor 16. A voltage meter 17 is connected between the conductors 15 and 16. Plates 18 of the tubes are connected to conductors 19 connected to the opposite ends of an inductance coil 20, hav'- 8 rto the opposite ends of the inductance coil l27, which is provided with a center tap 28 9 l which is included a milliampere meter 35,

and has its free end provided with a wrist clamp 36. The conductors 31 and 34 and the inductance coil constitute what I shall term the output circuit.

.Inductively connected to the central por-l tion ofthe grid coil 27 is a coil 37A of very few turns of wire. One end of the coil 37 is provided with a conductor 38 and the opposite end of the coil with a conductor 39. The free ends of the conductors are connected to a variable non-inductive resistance 40. This resistance is preferably of the carbon disc type which is mounted in the handle 41 of the knife 33. The handle of said knife is provided with a slot 42 in which is mounted an arm 43 having its inner endsupported against a conductor disc 44 and its opposite end pivotally connected to a suitable bracket 45 projecting outwardly from the handle 41.

The arm 42 includes a portion 46 which extends substantially parallel with the handle 41 and mounted in such a manner that as the handle 41 is held in the operators hand, his thumb is placed on the free end of the portion 46 and pressed inwardly, causing pressure to vbe applied to the discof the resistance 40, Land the resistance of the same decreased so that the current through the circuit formed by conductors 39 and the coil 37 may be increased. Releasing the handle 46 in a reverse manner decreases the current.

It will be seen that the conductors 38, 39, the resistance 40 and the coil 37 form a closed circuit, and on account of the coil 37 being placed in inductive relation with the coils 20 and 27, oscillating currents will be produced in said circuit.

The coil 37 is mounted in such a manner relative to the coils 20 and 27 that a portion of the energy transferred from the plate coil 20 tol the grid coil 27 will be consumed by the auxiliary circuit formed by the conductors 38, 39 and the coil 37, and thus providing means whereby the energy from the grid coil to the output circuit may be controlled so b that the current of the output circuit may be increased or decreased.

In-actual construction all four inductance coils are mounted in a concentric manner, one :'60

Within the other, in such manner that any one of said coils will be in inductive relation with all of the other coils.

Connected 'to the conductors 26 is a conductor 48 in which is included a variable condenser 49. v

0n account of the id coil 27 being in inductive relation Wit the coil 20, the condenser 49 is made to tune the id circuit and also control the frequency of t e plate circuit, thus providing a single control for tuning said circuits. The condenser 32 provldes means for tuning the output circuit in resonance with the grid and plate circuits after the clamp 36 has been placed on the patients wrist, and after the knife 33 has been placed in operative relation on the body. Tuning of this circuit .after` the instruments have thus been placed is necessa due to the fact that the capacity of the b y of one patient is different from that of another patient.

AIn the drawing I have illustrated the lament and plate circuits with `iixed voltages.

. These voltages may be varied if so desired,

but I find under ordinary conditions that the variable condenser 49 provides ample means for'varying the frequency of the oscillator.

The operation of my circuit is substantiall as follows: On account of the coils 2O and 2 being mounted in inductive relation, the energy from the battery 23 may be fed to the coil 20 and to the plates'18, and from the coil 20 to the coil 27 to cause the tubes to oscillate in the usual manner and in opposite phase, so that the amplitude of oscillations of the output circuit is thus increased from what would be produced if a single oscillator were employed. This provides one means for producing extremely high eiliciencyjof the circuit.

The condenser 49 is adjusted so that the tubes oscillate at the desired frequency, which isdetermined by the action of the meter 24. The clamp 36'is then placed on the patients wrist and the knife 33 applied to the body to form a closed output circuit. The condenser 32 is then adjusted and a reading taken from the meter 35, so that the plate circuit and the output circuit are in resonance. As before described, .it will be seen that energy will be absorbed by the auxiliary circuit, the amount of which is controlled through the variable resistance 40, and which, on account of ab sorbing a portion of the energy from the plate circuit will effect the amount of energy transferred to the coil 3() and to the output circuit. Assuming that the filament Vand plate voltages are maintained constant, then it will be seen that a constant amount of energy is'be- I ing delivered to the oscillating tubes, and consequently a constant amount of energy would e transferred to and divided between the coils 20 and 27, so that the sum of the currents of the auxiliary circuit and the output cir-v cuit is always equal to the total output of the oscillator. Y It will, therefore, be seen that any variation of the current of the auxiliary circuit will vary the current of output circuit. It will further be seen that inasmuch as the input and output energies are held constant any tendency toward changing the frequency l of the oscillator, due to variation of the output currents, is eliminated, and inasmuch as all of the inductances and capacities of the circuits are maintained constant during a 5 given operation, it will be seen that any desired frequency of the oscillator may be maintained throughout the entire operation, and at the same time the amount of the output circuit may be varied to suit the operator, to increase or decrease the cutting action of the knife. It should be understood that the actual cutting of the knife consists in a separation of the cells forming the tissues or muscles| due to the electric influence on said cells, 5 rather than by actually severing as with the ordinary surgical knife.

I claim as my invention:

l. In an electro-therapeutic apparatus the combination of an oscillatory circuit, a vacuum tube included in said circuit and comprising a grid and a plate circuit inductively coupled with each other, means for establishing in said circuit a variable predetermined high frequency oscillatory current, a variable capacity in said grid circuit for varying selectively the constants of said grid circuit, to thereby establish in the said oscillatory circuit an oscillatory current of predetermined frequency, a patients circuit, means for inductively coupling said patients circuit to said oscillatoryiclrcuit, means for varying the constants of said patients circuit whereby it may be brought into resonance with said oscillatory circuit, and means for including anmatomical member in said patients circu1 2. In an electro-therapeutic apparatus the combination of an oscillatory circuit, a vacuum tube included in said clrcuit and comprising a gridrand a plate circuit inductively `coupled-'with each other, means for establishing in said circuit a variable predetermined high frequency oscillatory current, a variable capacity 1n said grid circuit for varying selectively `the constants of said grid circuit, to thereby establish in the said oscillatory circuitY an oscillatory current of predetermined frequency, a patlents circuit, means for inductively coupling said patients circuit to said oscillatory circuit, means for varying the constants of said patients circuit whereby it may be brought into resonance with said oscillatory circuit, means for including an anatomical member in said patients circuit, 5 an auxiliary absorbent circuit inductively coupled to the said grid circuit, and means for varying the amount of current in said auxiliary absorbent circuit for varying the amount of current in the patients circuit.

o 3. In an electro-therapeutic apparatus the combination of two vacuum tubes, grid circuits for the tubes inductances included in the grid circuits, plate circuits for the tubes, inductances included in the 5 said inductances in the grid an late circuits, plate circuits ,tubl 

